I’ve been driving a Zündapp KS 750 motorcycle for forty years and as for today I never, ever accidentaly, meaning unwittingly, activated the blockade of the differential.
Yes, there was one time, after a night ride, when I left the blockade of the differential on. In the morning I totally forgot that, and I started the engine. As long as I was driving through a rough terrain, I wasn’t actually noticing that the differential isn’t working. But when I reached relatively even gravel road, I realized something is wrong. Driving straight wasn't problematic, but I had to actually force the motorcycle to make a turn. I stopped and started looking for the reason of this strange behaviour. There were no damages in front suspension, but then I noticed the lever of the differential blockade – I moved it and the problem was solved. Probably in the evening, when I finished the ride, I was so tired, that I totally forgot to de-activate the blockade.
I sometimes hear stories of the drivers who, during getting on or off a motorcycle, are moving the lever of the differential blockade foreward, even though the constructors invented a special protection which should prevent an unintentional dislocation of the lever.
The original blockade lever of the differential. Catalogue no. 1106
For me it still is an unfathomable mystery, how one can activate the blockade of the differential by accident. Nonetheless such accidents must have been quite frequent, otherwise how explain additional protections mounted on the lever, such as leather belts or various kinds of bands. Such protections probably are pretty useful, but may be problematic when there is a necessity of quick activation of the blockade.
The Finns found a good solution. In 1944 Zündapp Werke delivered to the finnish army 264 motorcycles with complete equipment (apart from tires on spare wheels) – they intended to deliver more machines, but during hard bombing of Szczecin on the 17th of August 1944, 36 motorcycles were destroyed in harbour magazines.
Probably, although I doubt it, the unintetnional activations of the blockade must have occured frequently, causing accidents. I cannot imagine any other reason why there was contructed and produced a special, additional protection of the lever of the differential blockade.
This protection completely eliminates the possibility of accidental activation of the blockade. Of course there are people who can damage literally anything, including something as simple as a steel ball.
Original, additional lever mounted in „finnish” motorcycle.
I had been hearing rumors about this additional protection for years, but for a very long time I’ve never seen it, even in the picture. It was to me like a Yeti – everyone heard about it, no-one seen it. The situation changed when I found such a tiny lever mounted next to „traditional” blockade lever in the motorcycle bought from Finnland.
We decided to produce a replica of additional protection of the blockade and I believe we did it pretty well. Below I present pictures showing reconstructed lever and the description of its operation.
The additional lever set to the position „blockade of the inclusion”
The additional lever set to the position „the blockade may be switched on”
To assemble the additional blockade, it is enough to replace one element of the original blockade lever, shown in the picture below, marked with an „A”, with a lever of our production (catalogue no. 1106-1), where the „A” element is an integral part of the set.
And finally: how does this blockade work? The lever is clamped by a spring, which in turn is held down with a castellated nut. The nut is protected by a cotter pin. In the „blockade” position the lever is set orthogonnaly to the motorcycle axis and its catch rest on the „A” element.
To unblock, the end of the lever (ended with a ball) has to be slightly lifted up (the catch of the lever will be above the surface of the „A” element) and moved backwards. The operation is very easy and fast to perform, and it doesn’t require taking off of the gloves.